/*
 * Copyright 2021-2022 Haiku, Inc. All rights reserved.
 * Released under the terms of the MIT License.
 *
 * Copyright 2008, Dustin Howett, dustin.howett@gmail.com. All rights reserved.
 * Copyright 2004-2010, Axel Dörfler, axeld@pinc-software.de.
 * Distributed under the terms of the MIT License.
 *
 * Copyright 2001, Travis Geiselbrecht. All rights reserved.
 * Distributed under the terms of the NewOS License.
 */


#include "arch_smp.h"

#include <boot/stage2.h>


//#define TRACE_SMP
#ifdef TRACE_SMP
#       define TRACE(x...) dprintf(x)
#else
#       define TRACE(x...) ;
#endif


extern "C" void smp_trampoline(void);
extern "C" void smp_trampoline_args(void);
extern "C" void smp_trampoline_end(void);

struct gdtr {
    uint16 limit;
    uint32 base;
    unsigned char null[8];
    unsigned char code[8];
    unsigned char data[8];
} __attribute__((packed));

// Arguments passed to the SMP trampoline.
struct trampoline_args {
        uint32 trampoline;              // Trampoline address
        uint32 gdt;                     // GDTR
        uint32 page_dir;                // page directory
        uint32 kernel_entry;            // Kernel entry point
        uint32 kernel_args;             // Kernel arguments
        uint32 current_cpu;             // CPU number
        uint32 stack_top;               // Kernel stack
        volatile uint32 sentinel;       // Sentinel, AP sets to 0 when finished

        // smp_boot_other_cpus puts the GDTR here.
        struct gdtr gdtr;
};


void
copy_trampoline_code(uint64 trampolineCode, uint64 trampolineStack)
{
        TRACE("copying the trampoline code to %p from %p\n", (char*)trampolineCode, (const void*)&smp_trampoline);
        TRACE("size of trampoline code = %" PRIu64 " bytes\n", (uint64)&smp_trampoline_end - (uint64)&smp_trampoline);
        memcpy((char *)trampolineCode, (const void*)&smp_trampoline,
                (uint64)&smp_trampoline_end - (uint64)&smp_trampoline);
}


void
prepare_trampoline_args(uint64 trampolineCode, uint64 trampolineStack,
        uint32 pagedir, uint64 kernelEntry, addr_t virtKernelArgs,
        uint32 currentCpu)
{
        trampoline_args* args = (trampoline_args *)trampolineStack;
        args->trampoline = trampolineCode;

        args->gdt = (uint32) &args->gdtr;
        args->gdtr.limit = 23;
        args->gdtr.base = (uint32)(uint64)args->gdtr.null;
        #define COPY_ARRAY(A, X0, X1, X2, X3, X4, X5, X6, X7) \
                { A[0] = X0; A[1] = X1; A[2] = X2; A[3] = X3; A[4] = X4; A[5] = X5; A[6] = X6; A[7] = X7; }
        COPY_ARRAY(args->gdtr.null, 0, 0, 0, 0, 0, 0, 0, 0);
        COPY_ARRAY(args->gdtr.code, 0xff, 0xff, 0, 0, 0, 0x9a, 0xcf, 0);
        COPY_ARRAY(args->gdtr.data, 0xff, 0xff, 0, 0, 0, 0x92, 0xcf, 0);
        #undef COPY_ARRAY
        //TODO: final GDT

        args->page_dir = pagedir;
        args->kernel_entry = kernelEntry;
        args->kernel_args = virtKernelArgs;
        args->current_cpu = currentCpu;
        args->stack_top = gKernelArgs.cpu_kstack[currentCpu].start
                + gKernelArgs.cpu_kstack[currentCpu].size;
        args->sentinel = 1;

        // put the args in the right place
        uint32 * args_ptr =
                (uint32 *)(trampolineCode + (uint64)smp_trampoline_args - (uint64)smp_trampoline);
        *args_ptr = (uint32)trampolineStack;
}


uint32
get_sentinel(uint64 trampolineStack)
{
        trampoline_args* args = (trampoline_args *)trampolineStack;
        return args->sentinel;
}